Method for the cold spurting of tubes and thin-walled metal pipes of lead, tin, and especially aluminium



Jan. 15, 1924. T v 1,480,843

F SINGER METHOD FOR THE com) RTING oF'TuB S AND-THIN WALLED METAL PIPES OF LE TIN, ANDES'PECIALLY ALUMINIUM Filed Feb. 21. 1922' ig-L Tatented Jan. 15, 1924.

UNHTEE STATES attests j FATENT QFFHQE.

FRITZ SINGER, F NUREMBERG, GERMANY, ASSIGNOR T0 FRITZ NEUMEYER A.-G., OF NUREMBERG, BAVARIA, GERMANY.

METHOD FOR THE COLD SPURTING OF TUBES AND THIN-WALLED METAL PIPES 0F LEAI), TIN, AND ESPECIALLY ALUMINIUM.

Application filed February 21, 1922. Serial No. 538,349.

To all whom it may concern:

Be it known that I, FRITZ SINGER, a citizen of the German Republic, residing at Nuremberg, Germany, have invented certain new and useful Improvements in Methods for the Cold Spurtin of Tubes and Thin- Walled Metal Pipes 0 Lead, Tin, and Especially Aluminium, of which the following is a specification.

This invention relates to a method for the production of compressible tubes and thin-walled metal tubes of lead, tin, and especially aluminium by the extrusion (or cold squirting) process and it consists in using prismatic, preferably square blanksp The sheet metal plates can be cut into square blanks almost without-waste whilst, if circular blanks are stamped out, which have been hitherto used exclusively for the purpose, considerable waste is left over. The transformation of this waste material into new plates of sheet metal causes great expenses which are saved according to this invention.

Square blanks have been used already for the warm pressing of thick-walled iron hollow bodies and it has been further pro posed, although without success, to use such square blanks for the warm pressing of brass cartridges. Square blanks have been further used for swaging. These blanks are however of a different kind than those used according to the novel method. The square blanks of known type are forged, hot pressed or blanks of larger size are first sawn off from prismatic rods, the shaping of which requires the same amount of material and the same work as the shapin of circular blanks. The savin of material, which is one of the principa objects of this invention, is of no account. Erhardts pressing process, which is a punchin process, uses prismatic work pieces in or or to provide the shortest way of escape for the material to be displaced by the mandrel. The Erhardts pressing process has the object to reduce as much as possible the work to be done and the'strain on the tools. The use of square blanks in swaging has for its obw-ject to improve the texture by the greater transforming work.

All these processes require hot working which means that the workin is done at a temperature at which the solidification and.

hardening of the metal at the state of production is destroyed. The malleability of the material in the heat is practically limited only by the cooling of the metal caused by the tools.

According to this invention the cold method is used in which the hardening and solidification of the material is increased to the maximum. The production oftubes,

especially of thin walled aluminium tubes, submits per se the metal to the utmost stress. In one pass a tube-shaped body is produced from a circular blank 4-5 mm. thick, the thickness of the wall of said body being only 5-10/100 mm. This requires pressures exceeding 100 kilograms per square millimeter, whilst in the hot process the pressures amount only. to 1020 kilograms per square millimeter. The highest possible demands are therefore made on the tools inthe manu facturing of aluminium tubes. The transformation which takes place when the tubes are being produced by the cold process is quite different from the transformation which takes place in the hot process. In the hot process segments have to be filled in by tangential and radial displacement of. v

the metal but in the working process accord-- ing to this invention the very complicated formation of a conical body with neck part is in question, which correspond tothe collar and neck of the finished tube, the formation of. the wall of the tube beginning only after this. It could not beexpected that this preliminary forming would be successfuland that the material would remain intact so that the finished tube was free from cracks and pores, as even inthe manufacturing of manufacturing of tubes from circular blanks one ought to think that it would be quite useless to increase this stress at the transformation by using square blanks instead of the circular blanks.

Although for the hot pressing of hollow bodies of simple form and with thick walls the use of square blanks had been known' already nobody had thought hitherto, for

the reasons mentioned, of using such blanks for the. production of leadtinor aluminium tubes by the cold extrusion process.

This idea has been realized by the present invention notwithstanding all the serious reasons which were against it. The considerable econom cal advantages resulting from this improved (method are obvious. Specially the application of the method to the manufacturing of aluminium tubes is an important progress as it is much more difficult to utilize the waste material from the manufacturing of tubes from aluminium than it is to utilize the waste of other ma- *terial.

' agonal section and in plan view.

ing die. a, t

' ig. 3 illustrates 1n longitud nal section b shape.

Fig. 2 shows in longitudinal section and in plan view this blank inserted in the pressand in plan view, the first alteration of Fig. 4 illustrates in longitudinal section the second and final alteration of shape.

As usual the die for the production of the tube by extrusion consists of the part a de signed to form the tube=collar, of the ring I) the inner diameter ,0? of which determines the outer diameter of the tube, of the pressing punch f with the collar-forming cone 9, of the thin mandrel h for the formation of the neck and of the transition bead 2', the diameter d of which determines the inner diameter of the tube and consequently the thickness of the' wall. In the working method only I the selection of the square blank is is novel. The square blank is of the size and thickness of the well known circular blanks and a diagonal length (5 which is equal to the inner'diameter of they ring I). to

The square blank has preferably a hole facilitate the insertion of and to guide the neck mandrel h.

I c1aim: ,Method for the production of compressible tubes and other thim-walled tubes of 

